Which characteristic defines FDA group I soft lenses?

FDA group I soft lenses are characterized by having a water content less than 50% and an ionic lens surface. This classification is important as water content significantly impacts the lens's performance, comfort, and compatibility with various eye conditions.

Lenses with lower water content tend to retain their shape better, making them easier to handle and fit on the eye. The ionic nature of the lens surface plays a critical role in enhancing wettability and biocompatibility, which are vital for comfort during wear. This means that lenses in this category are designed to interact well with the tear film, allowing for better overall eye health and reduced risk of complications.

Understanding these characteristics is crucial for practitioners when selecting lenses that will optimize patient comfort and fit.